We propose to study the basement membrane glycoprotein laminin, primarily from rodents, but later also from human. We will isolate laminin from cell culture and from tumors. The purified laminin will be characterized in terms of amino acid and carbohydrate composition and numnber and size of subunits. We will produce antibodies to laminin and use these to develop quantitative immunoassays (enzyme- and/or radioimmunoassays) for the measurement of laminin in biological fluids and for localization (by immunofluorescence and/or immunoperoxidase techniques) of laminin in tissue. We hypothesize that laminin is localized to basement membranes because it is specifically bound to other component(s) of the basement membranes and/or interacting with cells on the basement membrane. We will therefore study the interaction of laminin with known basement membrane components such as collagens and proteoglycans and with cells. These studies will be done using enzyme- and radio-affinity assays and cell attachment assays, respectively. We will also look for now unrecognized laminin ligands using affinity chromatography on laminin coupled to Sepharose. These studies will contribute to the understanding of the structure and function of basement membranes in normal and abnormal development, and in human disease processes.